Correction: you need 2 planes, assumng you only do the tower part. If you do the rest you need four (4) planes, a pentagon, and a field in PA. Now if the FBI doesn't have you on a watch list at this point you can proceed with your plan. Just 1 detail: cost.
Boeing 757-200 (Flight 93): $3.5M-11.27 USD Each
Boeing 767-200 (Flight 175) $200M USD Each
Boeing 767-223 (Flight 11) $190M USD Each
Boeing 757-223 (Flight 77) ≈$15M USD Each
North and South Tower $3.52B USD
Pentagon $1.19B USD
Flight 93 Memorial $60M USD
Total: $5178500000-$5186700000
